ABSTRACT
Imagine a recipe that has an error. It calls for too much or too little of an ingredient, leaves one out, or perhaps includes something not quite right. Correcting the instructions can perhaps salvage the dish. Compensating for or correcting errors is the idea behind the two biotechnologies discussed in this chapter. Gene therapy adds a working copy of a gene that is missing or mutant in a cell, but it does not remove the existing gene. Gene editing is more precise than gene therapy because it can add, remove, or replace a gene. Genome editing refers to editing more than one gene at a time. Gene therapy and gene/genome editing are performed on the cells that are affected in a particular disease, or alter other cell types in a way that counters symptoms.
